The long-term goal of the proposed research is the effective implementation of residual limb volume management strategies on prosthesis users so as to enhance their clinical outcomes, health, and quality-of- life. The focus of this application s to uncover knowledge essential to accomplishing this goal. The specific aims of the proposed research are to determine the influence of different activities and accommodation strategies on residual limb diurnal fluid volume change, and how they relate to comfort and performance of individuals with trans-tibial amputation. An additional goal is to create and evaluate a novel accommodation solution for people who are prescribed, but choose not to use, residual limb volume management strategies, such as changing prosthetic sock ply. To accomplish the aims, a novel multi-channel bioimpedance analysis instrument developed in the previous funding cycle is used to assess diurnal fluid volume changes in the residual limbs of a group of trans-tibial (i.e., below-knee) prosthesis users. Clinical outcomes, including socket comfort, satisfaction, and perceived mobility are obtained using self-report measures, while percent time weight-bearing and use of accommodation strategies are measured with custom instrumentation. It is expected that limb volume change negatively correlates with user satisfaction, comfort, and mobility, and that use of volume accommodation strategies, such as sock addition and intermittent doffing (i.e., removing the socket) enhances these outcomes. A novel management alternative we introduce for people who require, but choose not to use volume management strategies, is a timely release of socket pressures at key locations on the limb so as to augment limb fluid volume recovery. This strategy, informed by the results of the proposed research, is expected to be equally or more effective than sock accommodation towards enhancing outcomes. The relevance of the proposed application to public health is better understanding of how residual limb fluid volume changes impact users' experience with a prosthesis, clinically-important outcomes related to residual limb health, and users' performance in life activities. Currently, it is unknown where within the residual limb fluid volume changes occur or how much change can be tolerated without negatively affecting prosthetic fit. Beyond the grant period, it is anticipated the proposed research will be extended into clinical tools that allow practitioners to isolate limb fluid volume change problems from other issues such as improper componentry or alignment. Potentially, the efforts described here can be extended to other areas where devices require a secure and intimate fit with human tissues, including trans-fermoral prosthetics, upper-limb prosthetics, and orthotics.